EMI Registry

Description

EMI

European Middleware Initiative (EMI) is an FP7 EU funded project.

The Registry

The project is an implementation of the EMI Registry (part of the EMI project) specification to discover the services in a large-scale Distributed Computing Infrastructure (DCI).

Information Model

OGSA GLUE 2.0

OGSA GLUE2 is a standard from OGSA, which richly models Grid (Computing, User, Jobs and Storage) entities. EMI Registry highly endorses the service model of GLUE 2.0, while exposing the service information in XML as well as in JSON format.

JSON representation

Since there is no JSON rendering modeling GLUE 2.0 available, thus the new template has been derived, which maps the GLUE 2.0 entities with the JSON objects. Here is the brief example of a Service represented in JSON document.

JSON Service desrciption template

{
	"Service_Name":"ComputingService",
	"Service_CreationTime":{"$date":"2011-07-21T11:47:24.111Z"},
	"Service_Type":"job-management",
	"Service_Capability":["capability1","capability2"],
	"Service_QualityLevel":"production",
	"Service_Complexity":"complexity",
	"Service_Validity": 12313,
	"Service_Extensions":[{"key1":"value1"},{"key2":"value2"}],
	"Service_Endpoint_URL":"http://1", //Mandatory attribute (also considered as PK in SQL terms)
	"Service_Endpoint_Capability":["capability1","capability2"],
	"Service_Endpoint_Technology":"technology",
	"Service_Endpoint_InterfaceName":"interface",
	"Service_Endpoint_InterfaceVersion":["version1","version2"],
	"Service_Endpoint_InterfaceExtension":["extension1","extension2"],
	"Service_Endpoint_WSDL":"http://tempuri.org?EMIES-ResourceInfo.wsdl",
	"Service_Endpoint_SupportedProfile":["OGSA-BSP","OGSA-WSRF-BP"],
	"Service_Endpoint_Semantics":["semantic1","semantic2"],
	"Service_Endpoint_HealthState":"ok",
	"Service_Endpoint_HealthStateInfo":"state info",
	"Service_Endpoint_ServingState":"production",
	"Service_Endpoint_StartTime":{"$date":"2011-07-21T11:47:24.111Z"},
	"Service_Endpoint_IssuerCA":"issuer-dn",
	"Service_Endpoint_TrustedCA":["dn1","dn2","dn3"],
	"Service_Endpoint_DowntimeAnnounce":{"$date":"2011-07-21T11:47:24.111Z"},
	"Service_Endpoint_DowntimeStart":{"$date":"2011-07-21T11:47:24.111Z"},
	"Service_Endpoint_DowntimeEnd":{"$date":"2011-07-21T11:47:24.111Z"},
	"Service_Endpoint_QualityLevel":"production",
	"Service_ExpireOn":{"$date":"2011-07-21T11:47:24.111Z"}
}

GLUE 2.0 XML: Only the following GLUE 2.0 elements are supported

<glue:Service BaseType="Service" CreationTime="2011-07-21T11:47:24.111Z" Validity="0" xmlns:glue="http://schemas.ogf.org/glue/2009/03/spec_2.0_r1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://schemas.ogf.org/glue/2009/03/spec_2.0_r1 GLUE2.xsd ">
	<glue:ID>4e5e2f27ca91287bab38ba8f</glue:ID>
	<glue:Name>ComputingService</glue:Name>
	<glue:Capability>capability1</glue:Capability>
	<glue:Capability>capability2</glue:Capability>
	<glue:Extensions>
		<glue:Extension>
			<glue:LocalID>glue:LocalID</glue:LocalID>
			<glue:Key>key1</glue:Key>
			<glue:Value>value1</glue:Value>
		</glue:Extension>
		<glue:Extension>
			<glue:LocalID>glue:LocalID</glue:LocalID>
			<glue:Key>key2</glue:Key>
			<glue:Value>value2</glue:Value>
		</glue:Extension>
	<glue:Extensions>
	<glue:Type>job-management</glue:Type>
	<glue:Endpoint BaseType="Entity">
		<glue:ID>4e5e2f27ca91287bab38ba8f<glue:/ID>
		<glue:URL>http://bbd14a9b-0267-4479-a65d-14a04ba52043</glue:URL>
		<glue:Capability>capability1</glue:Capability>
		<glue:Capability>capability2</glue:Capability>
		<glue:InterfaceName>EMIES-ResourceInfo</glue:InterfaceName>
		<glue:InterfaceVersion>1.0</glue:InterfaceVersion>
		<glue:InterfaceExtension>extension1</glue:InterfaceExtension>
		<glue:InterfaceExtension>extension2</glue:InterfaceExtension>
		<glue:WSDL>http://tempuri.org?EMIES-ResourceInfo.wsdl</glue:WSDL>
		<glue:SupportedProfile>OGSA-BSP</glue:SupportedProfile>
		<glue:SupportedProfile>OGSA-WSRF-BP</glue:SupportedProfile>
		<glue:Semantics>semantics</glue:Semantics>
		<glue:QualityLevel>development</glue:QualityLevel>
		<glue:HealthState>critical</glue:HealthState>
		<glue:HealthStateInfo>glue:HealthStateInfo</glue:HealthStateInfo>
		<glue:ServingState>closed</glue:ServingState>
		<glue:StartTime>2001-12-31T12:00:00</glue:StartTime>
		<glue:IssuerCA>glue:IssuerCA</glue:IssuerCA>
		<glue:TrustedCA>glue:TrustedCA</glue:TrustedCA>
		<glue:DowntimeAnnounce>2001-12-31T12:00:00</glue:DowntimeAnnounce>
		<glue:DowntimeStart>2001-12-31T12:00:00</glue:DowntimeStart>
		<glue:DowntimeEnd>2001-12-31T12:00:00</glue:DowntimeEnd>
		<glue:DowntimeInfo>glue:DowntimeInfo</glue:DowntimeInfo>
	</glue:Endpoint>
</glue:Service>

As you have already noticed in the JSON document above that the GLUE 2.0 (sub-)elements are being mapped as JSON attributes. The mapping criteria is quite straight forward as the main Element under Service within XML document becomes the Service_Element, while the (sub-)child elements are represented as Service_Element_SubElement.

Security Model

Authentication

The client authentication is leveraging from SSL/TLS. This imply the registry user should possess an X.509 certificate for service registration as well as discovery

Authorization

The authorization model is being carried out using the PUSH model, where the attributes such as role, organization etc.. are being fetched at the registry while receiving the request

Implementation Remarks

• The registry is implemented in Oracle JAVA 6

  • To expose the REST-ful resources, Oracle’s Jersey (the reference impl. of JAX-RS) is being used

• Powerful database back-end on MongDB

• Maven 2 for project management

• Documentation using maven site plug-in with asciidoc markdown

Changes

Version 1.1.1

• Adding Support for MongoDB Authentication

• Fix: return correct service endpoint URLs while GET-ting the /services/urls

• Fix: appropriately handling the empty directories while packaging

Version 1.1.0

• P2P: support for the global replication

• P2P: robust handling of the global list

• Improved RPM and Debian distributions

• Fix: status script

• add separate packaging bundles for SL5 and SL6

Version 1.0.0

Implemented most of the basic functionality described in the EMI Registry design document